8.36 putting the verb first

In formal or literary English, if the first verb in an 'if'-clause is 'should', 'were', or 'had', this verb is sometimes put at the beginning of the clause and 'if' is omitted. For example, instead of saying 'If any visitors should come, I will say you are not here', someone might say 'Should any visitors come, I will say you are not here'.

8.37

Instead of using a conditional clause containing the word 'be', you can often use a phrase consisting of 'if' followed by an adjective or a prepositional phrase. For example, instead of saying 'We will sell the car, if it is necessary', you can say 'We will sell the car, if necessary'.